In thin-film magnetic heads, as disclosed in Japanese Unexamined Patent Application Publication No. 2007-257815, for example, an end face of a main magnetic pole film (recording magnetic pole film) appearing at an air bearing surface (ABS) is shaped to have a bevel angle so as to prevent so-called “side-erasing”, i.e., overwriting of adjacent tracks. The bevel angle is set such that the end face of the main magnetic pole film has a larger width at a trailing side. Conversely, it must have an inverted triangular shape or an inverted trapezoidal shape having a smaller width at a leading side. However, this reduces a sectional area of the main magnetic pole to degrade writing performance.
Moreover, since the main magnetic pole of the thin-film magnetic head has a large-width portion and a small-width portion in such an arrangement as to send a magnetic flux from the large-width portion to the small-width portion, the magnetic flux from the large-width portion concentrates on the small-width portion. This easily causes magnetic saturation or magnetic flux leakage at the small-width portion, hindering improvement in writing performance.